Vibration damping system and method for variable speed wind turbines

Abstract

A vibration damping technique for a wind turbine system is described. The wind turbine system includes a vibration damper, which provides a variable signal to control torque produced by a generator of the wind turbine system. The variable signal is based on generator speed and has a first local peak value based on a resonant frequency of tower side-to-side oscillation.

Description

BACKGROUND [0001] The invention relates generally to the field of wind turbines, and in particular to an active vibration damping solution for variable speed wind turbines. [0002] Wind turbines are regarded as environmentally safe and relatively inexpensive alternative sources of energy. A wind turbine generally includes a rotor that has multiple blades which transform wind energy into a rotational motion of a drive shaft. The drive shaft is utilized to rotate a rotor of an electrical generator. The turbine rotor is rotationally coupled to the generator by a drive train comprising a gear box. The gear box steps up the relatively low rotational speed of the turbine rotor to a more appropriate speed for the generator to efficiently convert the rotational motion to electrical energy. The electrical energy may then be supplied to a utility grid. Typically, the drive train and the generator are housed in a nacelle mounted atop a tower. [0003] Wind shear on the rotating blades causes peri...

AI Technical Summary

Benefits of technology

The present invention provides a new way to reduce vibrations in wind turbines. It involves a system that adjusts the torque produced by the generator based on the speed of the wind. This adjustment is done through a signal that has two peaks - one at the resonant frequency of the tower and one at the resonant frequency of the drive train. The result is a more efficient and effective wind turbine system that can produce energy with less vibration.

Problems solved by technology

Wind shear on the rotating blades causes periodic angular accelerations and decelerations of the rotor, which in turn induces torque oscillations in the drive train.

Generally, the drive train is composed primarily of steel components and therefore, exhibits poor passive damping characteristics.

Poor damping causes excessive vibrations that adversely affect the life of the turbine components.

In such machines, the torque demand is no longer restricted to being proportional to slip, resulting in a loss of damping performance.

However, such designs often turn out to be inadequate due to one or more of the following reasons.

First, since turbines are often configured using components from different vendors, it is difficult to obtain accurate estimates of resonance frequencies of the drive train.

Secondly, current drive train damping solutions do not mitigate tower side-to-side oscillations, which coupled to the torque oscillations of the drive train.

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